In general, an olfactometer is a device that is used to produce odors in a precise and controlled manner so that olfactory thresholds and intensities for different stimuli can be measured. Olfactometers have been used for many years in a laboratory environment to conduct qualitative experiments using human subjects for market research in many different types of products, such as, but not limited to, foods, drinks, and perfumes. The information obtained through these experiments is valuable because it allows the manufacturer of such products to optimize the amount of odor producing stimulant included in the product to produce a desired result.
One common type of instrument that is used to study olfaction is a dilution olfactometer. Initially, the dilution olfactometer was used to determine the concentration at which an odor was detectable (i.e., threshold), but has more recently been used to also study a wide range of psychophysical questions. In operation, the dilution olfactometer is used to dilute a sample gas containing a stimulant with a clean gas (e.g., air or nitrogen) at various flow rates. The required blending of the sample gas and clean gas makes it challenging to optimize the flow of these gases in a repeatable and contamination-free manner. The difficulty in achieving repeatable results is made more difficult given that the sample gas is mixed with the clean gas in varying amounts so that threshold levels may be tested.
There have been attempts to provide improvements to the existing dilution olfactometer by providing various solutions for changing the concentration of the dilution flow, improving changeover time, and reducing contamination. However, the need to uniformly blend sample gas with clean gas inherently requires a fairly complex plumbing system and other flow control mechanisms, which increases the cost of manufacturing these types of devices.
Accordingly, there exists a need for an olfactometer that produces test samples that have a consistent concentration, provides a simple construction that reduces the possibility of cross-contamination, allows for the testing of multiple stimulants at a time, and allows for the rapid interchangeability of samples during the testing process. The present invention fills these, as well as other, needs.